 $\bigoplus _{p\in P}{\mathbb {F}}_p$-systems and multiple recurrence
$\bigoplus _{p\in P}{\mathbb {F}}_p$-systems and multiple recurrencePublished online by Cambridge University Press: 25 October 2021
Let  $\mathcal {P}$ be an (unbounded) countable multiset of primes (that is, every prime may appear multiple times) and let
$\mathcal {P}$ be an (unbounded) countable multiset of primes (that is, every prime may appear multiple times) and let  $G=\bigoplus _{p\in \mathcal {P}}\mathbb {F}_p$. We develop a Host–Kra structure theory for the universal characteristic factors of an ergodic G-system. More specifically, we generalize the main results of Bergelson, Tao and Ziegler [An inverse theorem for the uniformity seminorms associated with the action of
$G=\bigoplus _{p\in \mathcal {P}}\mathbb {F}_p$. We develop a Host–Kra structure theory for the universal characteristic factors of an ergodic G-system. More specifically, we generalize the main results of Bergelson, Tao and Ziegler [An inverse theorem for the uniformity seminorms associated with the action of  $\mathbb {F}_p^\infty $. Geom. Funct. Anal. 19(6) (2010), 1539–1596], who studied these factors in the special case
$\mathbb {F}_p^\infty $. Geom. Funct. Anal. 19(6) (2010), 1539–1596], who studied these factors in the special case  $\mathcal {P}=\{p,p,p,\ldots \}$ for some fixed prime p. As an application we deduce a Khintchine-type recurrence theorem in the flavor of Bergelson, Tao and Ziegler [Multiple recurrence and convergence results associated to
$\mathcal {P}=\{p,p,p,\ldots \}$ for some fixed prime p. As an application we deduce a Khintchine-type recurrence theorem in the flavor of Bergelson, Tao and Ziegler [Multiple recurrence and convergence results associated to  $F_p^\omega $-actions. J. Anal. Math. 127 (2015), 329–378] and Bergelson, Host and Kra [Multiple recurrence and nilsequences. Invent. Math. 160(2) (2005), 261–303, with an appendix by I. Ruzsa].
$F_p^\omega $-actions. J. Anal. Math. 127 (2015), 329–378] and Bergelson, Host and Kra [Multiple recurrence and nilsequences. Invent. Math. 160(2) (2005), 261–303, with an appendix by I. Ruzsa].
 ${F}_p^{\infty }$
. Geom. Funct. Anal. 19(6) (2010), 1539–1596.CrossRefGoogle Scholar
${F}_p^{\infty }$
. Geom. Funct. Anal. 19(6) (2010), 1539–1596.CrossRefGoogle Scholar ${F}_p^{\omega }$
-actions. J. Anal. Math. 127 (2015), 329–378.Google Scholar
${F}_p^{\omega }$
-actions. J. Anal. Math. 127 (2015), 329–378.Google Scholar $\frac{1}{N}{\sum}_{n=1}^Nf({T}^n(x))g({T}^{n^2}(x))$
. Convergence in Ergodic Theory and Probability (Columbus, OH, 1993) (Ohio State University Mathematical Research Institute Publications, 5). Ed. Bergelson, V., March, P. and Rosenblatt, J.. De Gruyter, Berlin, 1996, pp. 193–227.CrossRefGoogle Scholar
$\frac{1}{N}{\sum}_{n=1}^Nf({T}^n(x))g({T}^{n^2}(x))$
. Convergence in Ergodic Theory and Probability (Columbus, OH, 1993) (Ohio State University Mathematical Research Institute Publications, 5). Ed. Bergelson, V., March, P. and Rosenblatt, J.. De Gruyter, Berlin, 1996, pp. 193–227.CrossRefGoogle Scholar ${U}^3(G)$
norm. Proc. Edinb. Math. Soc. (2) 51(1) (2008), 73–153.CrossRefGoogle Scholar
${U}^3(G)$
norm. Proc. Edinb. Math. Soc. (2) 51(1) (2008), 73–153.CrossRefGoogle Scholar ${U}^{s+1}\left[N\right]$
-norm. Ann. of Math. (2) 176(2) (2012), 1231–1372.CrossRefGoogle Scholar
${U}^{s+1}\left[N\right]$
-norm. Ann. of Math. (2) 176(2) (2012), 1231–1372.CrossRefGoogle Scholar